Laboratory evaluation of the effect of composite modifier on the performance of asphalt concrete mixture

The composite modifier (CM) of asphalt concrete (AC) mixture containing crumb tire rubber, recycled plastic particles, and SBS was developed. The main objective of this study was to evaluate the effect of CM on the performance of AC mixture. Wheel tracking test, beam bending test, freeze-thaw indirect tensile test, and bending creep test of CM modified AC mixtures and the control mixture (AC mixture without CM) were conducted in laboratory. The results show the addition of CM in AC mixtures can significantly improve high temperature performance compared to the control mixture, but the unsuitable dosage of CM may have some adverse effect on low temperature performance and moisture susceptibility. Considered comprehensively, the optimum dosage of CM was determined to be 0.3%. The relationship between the low temperature performance and CM dosage was verified by the m/S and dissipation energy ratios (Wd/Ws) calculated using Burgers model parameters of the bending creep at 0 °C. Compared to the control mixture, the values of permanent deformation and creep rate of CM modified AC mixture were smaller, and the values of the parameters E1 and η1 of Burgers model for the bending creep at 35 °C were larger. It can be further verified that the addition of CM obviously improves permanent deformation resistance of AC mixtures at high temperature.